Heterocyclic Ruthenium complexes have been shown to be DNA intercalators. These planar compounds contain carbon-nitrogen aromatic rings that insert between AT and GC base pairs of DNA. The Ruthenium compounds used are tri-chelated Ru (II) compounds. The basic structure includes two 2,2-bipyridine and a varying third ligand, phen-alloxazine, phen-aminopteridine, phen-dimethylalloxazine, phen-diaminopteridine, and phen-pterin. Upon exposure to UV light, many of the Ruthenium compounds have been shown to cleave DNA. Results of varying concentration and UV exposure time is explored through gel electrophoresis to determine optimal conditions, observe quenching and to elucidate ligand effects. Cleavage mechanism is largely unclear, though reactive oxygen species (ROS) are suspected. Investigating the effects of different ROS inhibitors, such as dimethylsulfoxide, superoxide dismutase, and sodium azide, will hopefully provide insight into the mechanism. DNA intercalation is confirmed using viscosity experiments. A parallel investigation is also being conducted with Copper and Cobalt complexes. Initial investigation into toxicity is also being conducted on cancer cell lines. Because of their ability to be selectively activated upon ultraviolet exposure, these complexes have potential future applications in cancer therapy.